1. Field of the Invention
The present invention relates generally to surgical methods and systems. More particularly, the present invention relates to a method and system for registering the position of a robotically manipulated surgical tool with a preoperative image by transforming a data set representing at least a partial image of a long bone to a robotic coordinate system.
Robotic systems for assisting in a number of medical procedures have been proposed, including neurosurgical, laparoscopic, and orthopedic procedures. While the details of a particular procedure may vary widely, a number of such procedures rely on first obtaining a preoperative image of the region to be operated on, and subsequently robotically controlling a medical tool based on information in the preoperative image. The procedures are usually surgical but can also be diagnostic. A need thus exists for transforming the preoperative image (usually in the form of a digital data set obtained by conventional imaging techniques) to a coordinate system employed by the robot. In this way, the robot is able to navigate the surgical tool based on the image data set which is representative of the patient's actual anatomy.
Of particular interest to the present invention, robotically assisted total hip replacement surgery is performed by first imaging the femur, typically by computerized tomography (CT), and producing a digital bone image data set representative of the femur. Selection and positioning of an implant within the femur is then planned at a computer workstation, such as the ORTHODOC.TM. presurgical planning workstation developed by Integrated Surgical Systems, Inc., Sacramento, Calif., assignee of the present application. Once the doctor has planned the implant placement on the workstation, a digital data set including both the image data (patient anatomy) and the planned positioning of the implant is produced. It is then necessary to transfer this data set to a computer-controlled robotic system intended to perform the surgery, such as the ROBODOC.TM. surgical robot system which has also been developed by Integrated Surgical Systems.
Successful hip replacement surgery, particularly when using cementless implants, relies on the highly accurate creation of a cavity within the proximal (upper) end of the femur for receiving the implant. Deviations less than .+-.1 mm from the planned cavity placement are desirable. A critical requirement in achieving such accuracy is precise registration between the bone image data set and the coordinate system of the surgical robot.
Image registration within the robotic coordinate system requires correlation between the physical position of the patient body site to be operated on, e.g., the femur in total hip replacement and knee replacement procedures, the digital bone image set representing the body feature, and the robotic coordinate system. Such correlation may be achieved by registering the bone image data set with the actual position of the body feature within the robotic coordinate space by physically contacting a probe at the end of a manipulator arm of the robot against certain imaged features on the body part. The information thus obtained by the robot controller can then be used to register the image with the actual body site, e.g., an immobilized femur, within the operative space of the robot.
Prior to the present invention, the ROBODOC.TM. surgical robot system has relied on the surgical implantation of a pair of metallic pins on the distal (lower) end of the femur and one additional metallic pin in the proximal end of the bone. These pins, usually referred to as fiducial markers, are readily apparent in the CT image of the bone and can thus be relied on to register the bone image with the robotic coordinate space by engaging a probe placed on the manipulator arm against each of the pins. Such registration is described in detail in Taylor et al. (1994) IEEE Trans. Robotics Automat. 10:261-275.
While capable of achieving a high degree of accuracy and precision, the need to implant the marker pins subjects the patient to considerable operative trauma. For that reason, it would be desirable to eliminate the implantation of fiducial marking pins altogether, yet provide a system for registering a bone image data set to a robotic coordinate system. The elimination of fiducial marking pins would offer numerous advantages including reducing the cost of the overall procedure, reducing the overall complexity of the treatment, and thereby reducing the risk to the patient. By eliminating one current surgical procedure, postoperative pain and discomfort would be substantially reduced.
A further advantage of eliminating fiducial marking pins is improved distal fixation, as follows. Currently, the distal femur is typically stabilized by securing the lower leg below the knee joint. Fixation of the lower leg below the knee joint is necessary when using fiduciary markers because the surgeon needs access to the marker pins during surgery. This method of knee fixation is non-optimal because the femur bone is on the opposite side of the knee joint which is relatively mobile such that the femur is not well stabilized. By eliminating fiducial marking pins, the distal femur could be fixated by securing the knee directly.
A further advantage of eliminating fiducial marking pins is that a computer tomography image of the bone can be taken at any convenient time prior to surgery, even several months prior to surgery. In contrast, when fiducial marking pins are used, it is necessary to take the computer tomography image shortly after the pins have already been attached. Accordingly, prior to the present invention, it has typically been necessary to undergo pin implantation, computerized tomography imaging of the bone, and robotic surgery all together within a relatively short time frame.
As will be explained, the present invention provides a system for registering a bone image to a robotic coordinate system in which the use of pre-inserted fiducial marking pins is eliminated, thereby overcoming numerous deficiencies in the prior art.
2. Description of the Background Art
The ORTHODOC.TM. presurgical planning workstation and the ROBODOC.TM. robotic surgical system are described in a number of references, including the following: (1) Kazanzides, P., Zuhars, J., Mittelstadt, B. D., Taylor, R. H.: "Force Sensing and Control for a Surgical Robot," Proc. IEEE Conference. on Robotics & Automation, Pages 612-616, Nice, France, May 1992. (2) Kazanzides, P., Zuhars, J., Mittelstadt, B. D., Williamson, B., Cain, P., Smith, F., Rose, L., Mustis, B.: "Architecture of a Surgical Robot," Proc. IEEE Conference. on Systems, Man, and Cybernetics, Chicago, Ill., Pages 1624-1629, October, 1992. (3) Paul, H. A., Bargar, W. L., Mittelstadt, B., Musits, B., Taylor, R. H., Kazanzides, P., Zuhars, J., Williamson, B., Hanson, W.: "Development of a Surgical Robot For Cementless Total Hip Arthroplasty," Clinical Orthopaedics, Volume 285, Pages 57-66, December 1992. (4) Kazanzides, P., Mittelstadt, B. D., Zuhars, J., Cain, P., Paul, H. A., "Surgical and Industrial Robots: Comparison and Case Study," Proc. International Robots and Vision Automation Conference, Pages 1019-1026, Detroit, Mich., April 1993. (5) Mittelstadt, B., Kazanzides, P., Zuhars, J., Williamson, B., Pettit, R., Cain, P., Kloth, D., Rose, L., Musits, B.: "Development of a surgical robot for cementless total hip replacement," Robotica, Volume 11, Pages 553-560, 1993. (6) Mittelstadt B., Kazanzides, P., Zuhars, J., Cain, P., Williamson, B.: "Robotic surgery: Achieving predictable results in an unpredictable environment," Proc. Sixth International Conference on Advanced Robotics, Pages 367-372, Tokyo, November, 1993. (7) Cain, P., Kazanzides, P., Zuhars, J., Mittelstadt, B., Paul, H.: "Safety Considerations in a Surgical Robot," Biomedical Sciences Instrumentation, Volume 29, Pages 291-294, San Antonio, Tex., April 1993. (8) Mittelstadt, B. D., Kazanzides, P., Zuhars, J., Williamson, B., Cain, P., Smith, F. Bargar, W.: "The Evolution of A Surgical Robot From Prototype to Human Clinical Use," in Proc. First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Pages 36-41, Pittsburgh, Pa., September 1994.
Other publications which describe image registration in robotic surgical and other procedures include the following: (9) Grimson, W. E. L., Lozano-Perez, T., Wells III, W. M., Ettinger, G. J., White, S. J., Kikinis, R.: "Automated Registration for Enhanced Reality Visualization in Surgery," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 82-89, Pittsburgh, Pa., Sep. 22-24, 1995. (10) Nolte, L. P., Zamorano, L. J., Jiang, Z., Wang, Q., Langlotz, F., Arm, E., Visarius, H.: "A Novel Approach to Computer Assisted Spine Surgery," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume II, Session IV, Pages 323-328, Pittsburgh, Pa., Sep. 22-24, 1994. (11) Lavallee, S., Sautot, P., Troccaz, J., Cinquin, P., Merloz, P.: "Computer Assisted Spine Surgery: a technique for accurate transpedicular screw fixation using CT data and a 3-D optical localizer," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume II, Session IV, Pages 315-321, Pittsburgh, Pa., Sep. 22-24, 1994. (12) Potamianos, P., Davies, B. L., Hibberd, R. D.: "Intra-Operative Imaging Guidance For Keyhole Surgery Methodology and Calibration," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 98-104, Pittsburgh, Pa., Sep. 22-24, 1994. (13) Simon, D. A., Hebert, M., Kanade, T.: "Techniques for Fast and Accurate Intra-Surgical Registration," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 90-97, Pittsburgh, Pa., Sep. 22-24, 1995. (14) Peria, O., Francois-Joubert, A., Lavallee, S., Champleboux, G., Cinquin, P., Grand, S.: "Accurate Registration of SPECT and MR brain images of patients suffering from epilepsy or tumor," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume II, Session IV, Pages 58-62, Pittsburgh, Pa., Sep. 22-24, 1995. (15) Lea, J. T., Watkins, D., Mills, A., Peshkin, M. A., Kienzle III, T. C., Stulberg, D. S.: "Registration and Immobilization for Robot-Assisted Orthopaedic Surgery," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 63-68, Pittsburgh, Pa., Sep. 22-24, 1995. (16) Ault, T., Siegel, M. W.: "Frameless Patient Registration Using Ultrasonic Imaging," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 74-81, Pittsburgh, Pa., Sep. 22-24, 1995. (17) Champleboux, G., Lavallee, S., Cinquin, P.: "An Optical Conformer for Radiotherapy Treatment Planning," Proceedings of the First International Symposium on Medical Robotics and Computer Assisted Surgery, Volume I, Sessions I-III, Pages 69-73, Pittsburgh, Pa., Sep. 22-24, 1995.
Various systems for image registration using fiducial implants are also described in U.S. Pat. Nos. 4,991,579; 4,945,914; 5,094,241; 5,119,817; 5,097,839; 5,142,930; 5,211,164; 5,230,338; 5,222,499; and 5,397,329 to Allen.
A system and method for performing robotically assisted surgery is described in U.S. Pat. No. 5,086,401. Computer-assisted imaging and probe tracking systems are described in U.S. Pat. Nos. 5,383,454; 5,198,877; and WO 91/07726. Copending and recently allowed application Ser. No. 08/526,826, assigned to the assignee of the present application, describes a method and system for transforming a bone image into a robotic coordinate system by aligning a robotic probe within the medullary canal of the femur. Patent application Ser. No. 09/022,643, also assigned to the assignee of the present application, describes a method and system for transforming a bone image into a robotic coordinate system based upon registering between the robotic coordinate system and the image data set 1) two positional coordinates axially spaced apart along the bone and 2) a directional vector passing through at least one of the positional coordinates.